Motorized transmitter

ABSTRACT

An electrical protection signaling system capable of producing alarm signals after the loss of the primary power supply. Signal interference caused by several transmitters operating simultaneously in the event of a power failure is avoided. A simplified circuit arrangement has been provided to permit operation of the system under electrical fault conditions and the need for manual rewinding of mechanically driven transmitters has been eliminated.

United States Patent [72] Inventors Francis C. Evans Staten Island;

Fred 0. Johnson, Northport, both of N.Y. [21] Appl. No. 772,259 [22] Filed Oct. 31, 1968 [45] Patented Nov. 2, 1971 [73] Assignee American District Telegraph Company Jersey City, NJ.

[54] MOTORIZED TRANSMITTER 12 Claims, 10 Drawing Figs.

[52] 11.8. C1 340/292, 307/64, 340/276, 340/409 [51] Int. Cl G08b13/02,

G081: 25/00, H02j 9/04 [50] Field 01 Search 340/292, 293, 409, 215, 286, 287, 276, 213, 309; 307/64 [56} References Cited UNITED STATES PATENTS 2,441 ,502 5/1948 Muehter 340/292 2,938,197 5/1960 Cassell 340/292 X Primary Examiner-John W. Caldwell Assistant ExaminerScott F. Partridge Attorney-Charles B. Smith ABSTRACT: An electrical protection signaling system capable of producing alarm signals after the loss of the primary power supply Signal interference caused by several transmitters operating simultaneously in the event ofa power failure is avoided. A simplified circuit arrangement has been provided to permit operation of the system under electrical fault conditions and the need for manual rewinding of mechanically driven transmitters has been eliminated.

ALARM 'Y'PANSMIY 7E9 PATENIEUrmv2 I97! 73,618 069 SHEET u (1F 4 STI MOTORIZED TRANSMITTER BACKGROUND OF THE INVENTION Electrical protection systems, e.g., automatic sprinkler systems employed to protect buildings and other property against damage by fire, are usually provided with an electrical signaling system designed to produce automatic signal indications of changes in the condition of the sprinkler or other protective system. The signals may be received at a particular place within the protected premises or at a central station located some miles distant and connected to the premises by telephone lines leased for the purpose. In either instance, trained personnel are constantly on duty to receive incoming signals and to initiate appropriate remedial action upon their receipt.

Such signaling systems are provided with a variety of devices designed to monitor specific conditions and to initiate a distinctive signal upon a change in the condition being monitoredr The transmitted signal has two basic functions: one is to indicate the nature of the change of condition that has been detected and the other is to identify the particular device which has originated the signal since it is customary for economic reasons to connect many condition detecting devices to a single set of signal-receiving apparatus. The latter function is usually accomplished by associating a transmitting device with one or a closely related group of detecting devices with the transmitter so arranged as to produce a numerical code in the form of a series of current pulses when an associated detecting device is actuated. The current pulses are applied to the lines leading to the signal-receiving point where they are automatically recorded on a paper tape by means well known in the art. The operator, by reading the numerical code, is thus able to identify the source of the signal.

The nature of the signal is usually determined by the number of times the numerical code is repeated by the transmitting device. Each repetition is termed a round" of signals. Thus, according to one practice, a fouror five-round signal indicates an alarm condition, a two-round signal indicates a condition of less urgency while a one-round signal may either indicate an electrical fault on the signaling system or the restoration of the signaling system to the normal condition after an activity of some nature.

It is usual to reserve the alarm signal for a change of condition that is strongly indicative of the occurrence of fire, i.e., water starting to flow in the conduits of the sprinkler system as would occur when one or more sprinkler heads had fused. The two-round "supervisory" signal is employed for conditions of less urgency which nevertheless require attention. Typical examples are a low water level in the gravity tank supplying the sprinkler system, temperatures approaching freezing in the water supply, the closure of important valves in the sprinkler system, etc., or an electrical fault on the signaling system. The one'round signal indicates either restoration of normal conditions or an electrical fault on the electrical system. Electrical faults are not a matter of prime urgency since such systems are customarily designed to transmit alarm signals under fault conditions.

Signaling systems of this nature are well known and have provided meritorious service for many years. However, many such systems employ electrically controlled, spring-driven mechanisms to generate the coded signals and such mechanisms particular be manually rewound after operating. A more serious difficulty, however, is presented by a failure of the electrical power supply associated with the transmitting devices. While the transmitters are capable of producing a receiving signal when the supply voltage has dropped to a cor tain level, there remains the possibility of a "gray area" of voltage wherein the potential has not dropped enough to in itiate the warning signal but is not sufficient to transmit an alarm signal should such a condition occur during a time of low voltage. A further problem associated with power failures was that when the voltage did drop sufficiently to initiate the warning signal, all the transmitters associated with a particular power supply would operate simultaneously and produce a confusing clash" ofsignals at the signal receiving point.

Finally, the electrical switching apparatus employed to condition the system to permit the transmission of signals when open or ground faults existed on the system was complex and therefore both costly and difficult to maintain under field service conditions.

The principal object of the present invention has been the provision of a novel and improved electrical signaling system which overcomes the disadvantages of the prior art.

More particularly, it has been an object of the invention to provide a signaling system capable of producing alarm signals under low-voltage conditions after a low-voltage warning signal has been transmittedv Another object of the invention has been the elimination of the simultaneous transmission of a number of signals from a group of transmitters connected to a common power supply upon a failure of that power supply,

A further object has been the elimination of the necessity to manually rewind the transmitting devices after operation and the provision of means whereby the system may be restored to the normal condition from a remote place.

A feature of the present invention has been the provision of simplified switching means to condition the system for operation under electrical fault conditions.

Other and further objects, features and advantages ofthe invention will be apparent from the following description of the invention.

SUMMARY OF THE INVENTION The invention includes the provision of a secondary power source together with a Zener diode or the like for sensing a failure of the primary power source, a power supervisory relay for transferring the signal-transmittin g device to the secondary power source and a special contact on the power supervisory relay to initiate the transmission of a signal indicative of the failure of the primary power source. Another contact of the power supervisory relay is so arranged as to prevent more than one of the transmitters associated with a common power source from transmitting signals in the event of a power failure. Electrical motors have been employed instead of mechanically driven mechanisms for the signal transmitters thereby eliminating the need for manual rewinding after an operation of the system. Restoration olthe system may be accomplished from a remote place by means of shunting circuits arranged to bypass contacts which are open when in the operated condition. A cam-operated contact has been provided which disconnects the ground from the power supply at certain intervals to permit operation of the system under electrical fault conditions with simpler circuitry than was employed in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in greater detail with reference to the appended drawings in which:

FIGS. 1A and IB, when joined, are a schematic diagram of an electrical signaling system embodying the invention;

FIG. 2 is a partial schematic diagram illustrating the manner in which the code-generating wheels are connected to the signaling lines;

FIG. 3 is a partial schematic diagram illustrating the means employed to actuate signal annunciating devices located at the protected premises;

FIG. 4 is a schematic diagram illustrating the alarm transmitter code wheel, cam and switch positions in their normal condition;

FIG. 5 is a schematic diagram similar to FIG. 4 and illustrating the alarm transmitter cam and switch positions in their trouble condition;

FIG. 6 is a schematic diagram similar to FIG. 5 and illustrating the alarm transmitter cam and switch positions in their end of alarm condition;

FIG. 7 is a schematic diagram of one of the cam and switch assemblies of FIG. 6 illustrating their positions during the alarm transmission;

FIG. 8 is a schematic diagram illustrating the supervisory transmitter code wheel and switch positions in their normal condition; and

FIG. 9 is a schematic diagram illustrating the supervisory transmitting code wheel and switch positions in their trouble conditions.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. I, there are shown the basic components which comprise the electrical signaling system of the invention. While the system will be explained in conjunction with an automatic sprinkler system, those familiar with the art will recognize that the principles of the invention may be applied to other types of electrical protection systems with equal benefit and that the association with an automatic sprinkler system is for convenience of explanation only and is not to be construed as a limitation.

The typical values for resistors and capacitors shown in FIGS. IA and 1B in ohms and microfarads, respectively, as well as the identification of standard diodes and transistors and the operating voltages mentioned in the following description are also for illustrative purposes only and are not to be interpreted as limitations.

The three basic components are the power supply 10 including its self-supervising features, an alarm transmitter 11 designed to produce signals indicative of an urgent condition such as the detection of a flow of water in the conduits of the sprinkler system and a supervisory transmitter 12 which produces signals indicating low water level or low temperature in the gravity tank, closed gate valves, etc. Depending upon the requirements of the particular installation, the supervisory transmitter may be omitted or one or more additional supervisory transmitters 13 may be provided and wired in parallel with the first supervisory transmitter. In some cases, the alarm transmitter might be omitted and the power supply may be connected to one or more supervisory transmitters. The number of additional transmitters is limited primarily by the ampere-hour capacity of the standby battery to supply the current drain for the required number of hours while in the standby condition. These components will ordinarily be mounted in a single cabinet for convenience.

The power supply 10 includes a l2-volt battery I4 which might conveniently be of the nickel-cadmium type and is trickle-charged from a llO-volt AC source by a stepdown transformer and rectifier not shown. A capacitor C-l and a resistor 11-! are connected in series across the battery terminals to smooth ripples in the rectified supply voltage and to regulate the charging current respectively. The positive terminal 15 supplies operating potential to the supervisory transmitters l2, 13 via a conductor 16 and to the alarm transmitter 11 via a conductor 17 and from contact PS-I ofa relay PS. The return to the negative supply terminal 18 is via a conductor 19. Terminal I8 is grounded at 20 via conductor 21 and a contact K3-4.

The alarm transmitter 11 is provided with a code wheel CW (FIG. 4) and earns ATI, ATZ and AT3 which operate, respectively, multiple switches K1, K2 and K3. Switch Kl has a pair olcontacts designated m and n which cooperate with an armature mn. Switch K2 has two switch elements K2, and K2, which are formed by contact pairs f-g and 11-1, respectively, and respective armatures f and hi. Switch K3 has four switch elements K3,, K3,, K3,, and K3,. Switch element K3, is formed by contacts a and b and armature ab. Switch element K3, is formed by contact t" and armature c. Switch element K3, is formed by contact if and armature d. Switch element K3 is formed by contact e and armature e.

The normal position of the switches K1. K2 and K3 is illustrated in FIG. 4. Other positions thereof are illustrated in FIGS 5,6 and 7.

Supervisory transmitter 12 is provided with a code wheel SCW (FIG. 2), which will usually be identical to code wheel CW, and with cams STI and STZ (FIG. 8) which operate, respectively, multiple switches I'll, and K2,. Switch KI has contacts ns and ms which cooperate with an armature nms. Switch K2, has switch elements K2,, and K2,, formed, respectively by contacts fr, gs and armature fgs and by contact is and armature is. The normal positions of the supervisory transmitter switches is shown in FIG. 8; the trouble position thereof is shown in FIG. 9.

A l3.5-volt battery 22, which might be of the mercury type, is arranged to be coupled in parallel with the main battery 14 through the normally open back contact PS-I. Also in parallel with the batteries is a supervisory network consisting ofthe series connnected winding of the power supervisory relay PS and the collector-emitter circuit of a transistor TRN-I. Also included in the supervisory network and paralleling the relaytransistor combination is the series connection of a resistor R-Z, Zener diode REC-l and resistor R-3. The winding of relay PS is shunted by a diode REC-2.

Under normal conditions, the l2-volt supply is sufficient to break down the Zener diode REC-l, which might conveniently have a 9.l-volt rating, so that the voltage divider combination of resistors R-Z, R-3 provides a forward bias for the base of transistor TRN-I rendering it conductive. Relay PS is therefore normally energized and the back contact PS-I is open so that battery 22 is disconnected from the circuit and under no drain. The diode REC-2 protects transistor TRN-l when relay PS releases by providing a discharge path for the inductive surge.

The alarm transmitter 11 comprises an electric motor 23, a circuit including the detection devices and a motor control circuit all connnected in parallel between positive conductor 17 and negative conductor 19. The function of motor 23 is to drive the signal code generating wheel and to operate various cam-controlled contacts which condition the system according to immediate circumstances.

The signal code generating wheel for the alarm transmitter is indicated at CW in FIGS. 2 and 4. The motor 23 also drives cams ATI, AT2 and AT3. The cams ATZ and AT3 rotate at the same speed, which speed is one-sixth the speed of rotation of the signal code generating wheel CW and cam AT].

A complete cycle of operation for the alarm transmitter consists of six signal rounds, one of which is expended for the restoration signal after a previous operation, thus in the normal condition, the alarm transmitter is prepared to transmit up to five rounds of signals. A signal "round represents the transmission of an identifying code, e.g., a three-digit number, by intermittent interruption of the circuit to the central station or other location where the signal is to be acted on. Two rounds are transmitted for each revolution of the code wheel. The code wheel may be of any suitable type, e.g., as shown in U.S. Pat. No. 2,966,566 to Hube. The code wheel illustrated in FIG. 4 is of the commutator segment type as shown in U.S. Pat. No. 3,385,943 to Westphal.

One or more detecting devices are associated with the alarm transmitter and are connected in parallel between wire runs designated as the A-loop and the B-loop. Each detecting device has a normally open contact 24 which closes in response to the detection of a condition and thereby establishes a short circuit between the loops.

Each supervisory transmitter l2, 13 also comprises an electric motor 25, a circuit including the detection devices and a motor control circuit all connected in parallel between positive conductor 16 and negative conductor I). The function of motor 25 is the same as described for the alarm transmitter, i.e., it operates supervisory signal wheel SCW (FIG. 2) and cams STI and STZ (FIG. 8). However, the detecting devices have normally closed contacts 26 and are connected in series. A complete cycle of operation for a supervisory transmitter consists of three signal rounds, one of which having been expended for the previous restoration signal, leaves a two-round capacity in the normal condition.

The functioning of the system will now be described in detail for each of the several modes of operation. Alarm Signal With the system in the normal condition (FIG. 4), current flows to the alarm transmitter ll from positive terminal via conductor 17, front contact PS-l, resistor R4, the A-loop, front contact A4 of relay A; the winding of normally energized alarm relay A, front contact PS-Z of relay PS, the B-loop and conductor 19 to the grounded terminal 18 of battery 14.

The operation of any detecting device crosses the A- and B- loops at the operated contact 24, thereby shunting the winding of alarm relay A which becomes deenergized. Contact A-Z transfers opening the locking circuit for relay A and establishing a circuit for motor 23 via switch element KZ-l, back contact A-2 and the crossed loops to the negative conductor 19. Contact A-l also transfers and establishes a second motor circuit via switch element K3-l and back contact A-] to the negative conductor 19. Motor 23 starts to run and shortly thereafter cam-operated switch Kl transfers to establish a third motor circuit via conductor 27 and front contact Kl to the negative conductor 19.

Concurrently the second signal round (first round of the alarm) is being transmitted and another cam-controlled switch is operated to transfer switch elements K3-2, K3-3 and K3-4. Closing of switch element K3-2 shunts the A-loop, closing of contact K3-4 opens the connection to ground for reasons which will be made apparent hereinafter. Before the end of the second round of signals, cam-operated switch element KJ-l transfers to open the motor circuit established through the back contact Al.

During the third round of signals, cam-operated switch element K2-l transfers to the back contact, as shown in FIG. 7, thus opening the motor circuit through back contact A-Z but reestablishing the motor circuit through the back contact Al.

AT the completion of five rounds of signals (the end of the sixth round), contact K2-] is moved to a central position and is open on both sides, as shown in FIG. 6, thereby opening the motor circuit through back contact A-l. The motor is now operating only through front contact K1 and conductor 27 so that upon the immediately following transfer of contact Kl, power is removed from the motor and the braking resistor R-5 is connected across the motor winding to discharge the counterelectromotive force and bring the motor to a quick stop.

As mentioned above, the alarm transmitter is intended to transmit up to six rounds of signals, i.e., six spaced sets of identifying code digits. The first round is a reset signal after a previous transmission. Hence FIG. 4 illustrates the condition of switches K1, K2 and K3 before the second round commences. FIG. 5 represents the conditions of switches Kl, K2 and K3 at the end of the second round. FIG. 7 illustrates the transfer of contact of switch K2 which occurs during the third round. Finally, FIG. 6 represents the conditions of switches Kl, K2 and K3 at the end ofthe sixth round.

The various occurrences during transmission of an alarm are shown by the following tabulation:

(middle cum step] KJ-2 closes 1 (middle cam IlCp) KJ-J closes d (middle cam step) K34 opens e (bottom cam step) KJ-l transfers from h to a During Third Round K24 transfers from g to] End of Sixth Round (middle cam step) KZ-I transfers from {to center Kl transfers from n to m Motor 23 rtopr.

Restoration of Alarm Transmitter When the actuated detecting device has been returned to the normal open contact position, the alarm transmitter is restored to the normal condition by momentary closure of contact RS-l. Contact RS-l might be a key-operated switch mounted on the cabinet containing the transmitters or it could be a contact of a relay (not shown) arranged to be energized from a remote place. Either way, closure of contact RS1 shunts contact A-Z which is still on its back contact. Current therefore again flows to the winding of relay A which becomes energized and contacts A-l, A-2 transfer. A motor circuit is established through switch element K3-l, which is still on its back contact, and the front contact of A-l and the motor 23 starts, thereby initiating the one-round restoration signal.

During the transmission of the signal, switch element KZ-l returns to the normal position on the front contact, switch ele ments K34 and K3-3 open to remove the shunts from the A- and B-loops respectively, switch element K3-4 restores the ground connection and switch element K3-l transfers to the front contact. Meanwhile, however, switch K] has transferred to the front contact to keep the motor 23 running. At the end of the transmission, i.e., at the end of the first round, switch Kl returns to the back contact thereby opening the motor circuit and connecting the braking resistor R-S to the motor winding. The transmitter is now back in the normal (FIG. 4) condition.

These occurrences are shown in tabular form thus:

[top of caml Fault Conditions If either the A- or B-loops should be broken at any point, relay A becomes deenergized and contacts A-l, A-Z transfer. Under these conditions, contact A-2 does not provide a motor circuit but contact A-l does via the front contact of switch element K3-l. Motor 23 starts the transmission of a signal and switch Kl transfers to establish a second motor circuit via conductor 27. Switch elements K3-2 and K33 close to shunt the A and B loops respectively and switch element K3-4 opens the connection to ground 20. Switch element K3-l then transfers and opens the first motor circuit via the back contact A-l. When switch K1 next transfers (it makes a complete cycle of operation during each round of signal transmission) the second motor circuit via conductor 27 is opened and the braking resistor R-S is connected, thus stopping the motor after a one-round trouble signal has been transmittedv The trouble signal represents a change from FIG. 4 to FIG. 5, i.e., from the end of the first round to the end of the second round.

Should the electrical fault be a ground on the A'loop, resistor R-4 protects the power supply from a dead short. Since the rest of the protection system is shunted by the accidental ground, equivalent to the alarm condition, relay A releases and contacts A-l. A 2 transfer to their respective back con tacts. One motor circuit is established via switch element KJ-l and contacts A4 and a second circuit via switch element KZ-l contacts A-2 and the accidental ground. The motor starts and switch Kl establishes a third motor circuit via conductor 27. Switch elements K3-2 and K3-4 shunt the A- and B-loops respectively and switch element K3-4 opens the connection to ground 20 thereby opening the motor circuit via the accidental ground since the battery is no longer grounded. Switch element KS-l then opens the motor circuit via the back contact A-l so that when switch Kl transfers, the motor is stopped as previously explained after the transmission of a one-round trouble signal.

A ground on the B-loop has no effect on the system because the B-loop is at ground potential normally. No signal is transmitted and none is needed because the system will perform all its functions normally under such conditions. In the unlikely event that a second accidental ground should then appear on the A-loop, the transmitter will transmit an alarm signal because the opening of switch element K3-4 does not remove the ground connection to the battery via the accidental ground on the A-loop.

Alarm under fault Conditions.

Under fault conditions, relay A has released, the A- and B- loops are shunted, the ground connection at 20 has been opened by switch element K34 and switch element K3-l has transferred to the back contact. Switch element K2-l and switch K1 are in their normal positions and a one-round trouble signal has been transmitted.

If the fault is an open on either of the loops, the subsequent operation of a detecting device, by interconnecting the loops, completes a motor circuit via switch element KZ-l, contacts A-2 and some combination of the loop shunting switch elements K3-2, K3-3 and the intact portion of the loop, depending on the location of the fault. The motor 23 starts and transmits a four-round alarm signal at which point it is stopped by the opening of the front contact of switch element K24 and the transfer of switch K1 in the usual manner.

if the fault had been a ground on the A-loop, the closure of the detecting device contact establishes a motor circuit to the negative terminal 18 allowing the transmission of a four-round alarm signal before the motor is stopped by the transfer of switch element K2-] and switch KI.

A ground on the B-loop has no effect as previously explained.

Power Failure In the event of a failure of the primary AC source, the signaling system will operate from the battery 14 for a number of hours determined by the ampere-hour capacity of the battery and the drain on the battery during the standby period. Eventually, the voltage of battery 14 will decrease to the 9.1- volt rating of Zener diode REC-l which will then stop conducting and so remove the forward bias for transistor TRN-I. The transistor becomes nonconductive, allowing the power supervisory relay PS to release. Contact PS-I transfers to connect the alarm transmitter 11 to the secondary battery 22. Concurrently, contact PS-Z opens, allowing the A relay to release and initiate a one-round trouble signal in the same manner as would occur if there were an open on one of the loops.

The transmitter is now capable of sending alarm signals by means of battery 22, the procedure being the same as described previously for operation when there is an open on a loop.

Restoration of normal voltage to battery 14 will cause Zener diode REC-I to break down, transistor TRN-l to become conductive and energize relay PS thus returning contacts PS-l, PS-Z to the normal position. Alarm transmitter 11 remains in the trouble position as it would be after sending a one-round signal in response to a fault on the loops.

Operation of the restoration switch RS-I shunts contact A-Z (the equivalent of the operation of one of the detecting devices) and a four-round alarm signal is transmitted followed by a one-round restoration signal. The system is now back in the normal condition.

Supervisory Signal With the system in the normal condition, current flows to the supervisory transmitter 12 from positive terminal 15 via conductor 16, resistor R-6, the contacts 26 of the detecting devices, contact S2 of normally energized supervisory relay S,

the coil of relay S and conductor I9 to the grounded terminal 18 of battery 14.

The operation of any detecting device supervisory contact 26 opens the circuit to supervisory relay 5 which thereupon deenergizes. Contact S2 thus opens to in turn open the locking circuit for relay S and contact Si transfers and establishes an energizing circuit for motor 25 via the back contact KI-IS to negative conductor 19. This position of switch element KZ-IS is illustrated in FIG. 8. The motor 26 starts to run and transmits a two-round signal. Shortly after the motor 25 starts, cam-operated switch element Kl-S transfers and establishes a second motor circuit via conductor 28 to the negative conductor.

Shortly before the end of the second signal round, camoperated switch element KZ-IS transfers, thus opening the first motor circuit and switch element K2-2S closes to place a shunt around contact S2. At the end of signal transmission, switch element Kl-S again transfers to open the second motor circuit and apply braking resistor R-7 which quickly halts the motor. Cam-operated switches Ll-S and KZ-S are then in the positions illustrated in FIG. 9.

Restoration of Supervisory Transmitter The supervisory transmitter may be restored either automatically or manually. If automatic restoration is desired, a strap 29 is installed to shunt the normally open restoration switch contact RS-Z. Consequently, when the actuated detecting device(s) returns to the normal condition and closes contact(s) 26, power is restored to relay S via the now closed contact K2-2S and strap 29. Relay S becomes energized; contact S2 closes to lock in the relay and contact S1 starts the motor via the front contact KZ-IS. Transmission of the oneround restoration signal begins and contact Kl-S transfers to establish the second motor circuit via conductor 28. Before the end of transmission, contact K2-2S opens and contact KZ-IS transfers thereby opening the first motor circuit. When transmission is complete, contact Kl-S again transfers to open the second motor circuit and apply braking resistor R-7. The system is now back in the normal condition with the camoperated supervisory switches in their FIG. 8 positions.

If manual restoration is desired, strap 29 is omitted and switch RS-2 is momentarily operated either from the control cabinet or remotely by means of a relay (not shown), Closure of switch RS-Z performs the same function as strap 29 and the sequence of restoration is the same as described for automatic restoration. For convenience, supervisory restoration switch RS-2 could be ganged with alarm restoration switch RS-l since the momentary closure of either has no effect on the as sociated transmitter when in the normal condition.

Fault Conditions An open or a ground fault on the line connecting the detecting devices will cause the supervisory relay S to dcenergize and transmit a two round signal as described under normal operation of the supervisory transmitter. In the event of a ground fault, resistor R6 protects the power supply from a dead short.

A power failure will cause the supervisory relay S to release, but no signal is transmitted because there is no potential available to run the motor. Battery 14 is unable to provide sufficient potential and the supervisory transmitter is isolated from secondary battery 22 by the power supervisory relay contact PS-l which is on its back contact in the event of a power failure. A one-round trouble signal, however, is transmitted by the alarm transmitter as described in connection with the operation under a power failure above. As a consequence, a confusing clash of signals from a number of transmitters is avoided as could occur under power failure conditions in the prior art.

Signal Generation The coded signals in the form of current pulses applied to the lines to the signal-receiving point are preferably generated by a commutator type of signal wheel well known in the signaling art and illustrated in FIG. 1 The alarm signal wheel is driven by motor 23 and consists of a nonconducting material on which copper is deposited in a pattern such that the circuit between the spring contacts riding on the surface of the wheel is broken and grounded to produce the desired sequence of current pulses. The supervisory signal wheel. driven by motor 25, is similar in construction and is connected to a separate signal line. Any additional supervisory signal wheels are connected in parallel with the first wheel and share the same signal line.

Local Signal Devices Under some circumstances it may be desirable to provide visual and audible signaling devices at the protected premises to annunciate the receipt of signals. Such annunciation is readily provided by means of an additional cam-operated contact switch element associated with the alarm transmitter and arranged to operate a transfer contact as shown in FIGS. 3-7.

Switch element K2-2 is arranged to operate simultaneously with switch element KZ-l and, since both normally open and closed circuits are provided, it is a simple matter to accommodate any type of local annunciation circuit.

While the invention has been described in connection with specified embodiments thereof and in specific uses, various modifications thereof will occur to those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. An electrical protection system of the type in which the happening of occurrences at a protected place as indicated by operation of one or more condition-sensing devices at said protected place are signaled to a remote place by means of one or more rounds of coded current impulses on a communication line joining said places, comprising:

a. a power supply unit having:

I. a primary source of DC operating potential;

2. a secondary source of DC operating potential coupled across said primary source to provide an operating potential in the event of failure of said primary source:

. an output terminal:

. current and voltage responsive means coupled across said primary and secondary sources and having transfer contacts arranged to connect said primary and secondary sources to said output terminal when either of said primary and secondary sources have a voltage equal to or above a selected level:

. a tertiary source of DC operating potential normally electrically isolated from said primary and secondary sources and from said output terminal; and

6. means including said transfer contacts to interconnect said tertiary source and said output terminal when both of said primary and secondary sources have a voltage below said selected level;

b. a transmitter having:

. a code wheel;

. an output signaling circuit electrically coupled to said code wheel for delivering rounds of current impulses to said communication line upon operation of said code wheel;

. a multielement switching mechanism having a plurality of successive switching positions;

4. an electric motor operatively coupled to said code wheel and said switching mechanism to operate said code wheel and said switching mechanism when operating potential is applied to said motor;

. operable circuit means including elements of said switching mechanism and interconnecting said electric motor and said output terminal and arranged, when operated, to apply operating potential to said electric motor;

6. electrical control means operatively associated with one or more of said condition sensing devices and electrically associated with said circuit means for operating the latter upon operation of one or more of said condition sensing devices whereby said circuit means applies operating potential to said electric motor and said 10 wheel supplies current impulses to said output signaling circuit; and

7. braking means responsive to current impulses coupled with said electric motor and arranged to stop the latter after a predetermined number of rounds of current impulses have been delivered to said output signaling circuit.

2. An electrical protection system as set forth in claim I in which said transmitter is provided with an additional electrical control means operatively associated with said current and voltage responsive means and electrically associated with said circuit means for operating the latter when both of said primary and secondary sources have a voltage below said selected level.

3. An electrical protection system as set forth in claim 2 in which said circuit means is provided with switching elements effective when said circuit means is operated by said additional electrical control means to cause a distinctive number of rounds of current impulses to be supplied to said output signaling circuit.

4. An electrical protection system as set forth in claim 1 in which there are provided a plurality of said transmitters.

5. An electrical protection system as set forth in claim 4 in which at least a selected one but not all of said transmitters have the operable circuit means thereof connected to said primary and secondary sources and in which said power supply is provided with means electrically to isolate said selected one or more of said transmitters from said tertiary source when said tertiary source is connected to said output terminal of said power supply.

6. An electrical protection system of the type in which the happening of alarm and supervisory-type occurrences at a protected place as indicated by operation of respective contacts of respective alarm and supervisory sensing devices at said protected place are signaled to a remote place by means of rounds of coded current impulses on alarm and supervisory communication lines joining said places, comprising:

a. a power supply unit having:

1. a primary source of DC operating potential;

2. a secondary source of DC operating potential coupled across said primary source to provide an operating potential in the event of failure of said primary source;

3. high and low side conductors coupled respectively to high and low potential sides of said primary and secondary sources;

4. a power supervisory circuit comprising a relay and a transistor coupled between said high and low side condoctors and arranged, upon a change in conductive condition of said transistor, to operate said relay;

5. a voltage sensitive circuit coupled between said high and low side conductors and having an intermediate potential point coupled to an element of said transistor to provide a bias potential thereto, said voltage sensitive circuit being arranged, when the voltage between said conductors at least equals a selected value to place said transistor in a selected conductive condition and when said voltage between said conductors falls below said selected value to place said transistor in a different conductive condition thereby to operate said relay;

6. a high side output terminal;

means including an armature and contact of said relay to connect said output terminal to said high side conductor; and

8. a tertiary source of DC operating potential comprising a local battery having its low side connected to said low side conductor and having its high side connected to another contact of said relay associated with said armature;

b. an alarm transmitter having:

1. an alarm signal code wheel;

2. an alarm signaling circuit electrically coupled to said alarm code wheel for delivering rounds of coded current impulses to said alarm communication lines upon operation of said alarm signal code wheel;

3. a first plurality of cam operated switches having a plurality of successive switching positions;

4. a first electric motor operatively coupled to said alarm signal code wheel and to said first cam-operated switches to operate said alarm signal code wheel and said first cam-operated switches when operating potential is applied to said first motor;

5. first operable circuit means including switches of said first plurality and contacts of at least one of said alarm sensing devices and arranged upon operation of the latter to intercouple said first electric motor, said out put terminal and said low side conductor to apply an operating potential to said first electric motor and to maintain said first electric motor operated during a first period of time in which selected rounds of coded current impulses representative of an alarm are applied to said alarm communication line; and

c. a supervisory transmitter having:

I. a supervisory signal code wheel;

2. a supervisory signaling circuit electrically coupled to said supervisory code wheel for delivering rounds of coded current impulses to said supervisory communication linc upon operation of said supervisory signal code wheel;

3. a second plurality of cam operated switches having a plurality of successive switching positions;

4. a second electric motor operatively coupled to said supervisory signal code wheel and to said second camoperated switches to operate said supervisory code wheel and said second cam-operated switches when operating potential is applied to said second motor; and

5. second operable circuit means including switches of said second plurality and contacts of at least one of said supervisory sensing devices and arranged upon operation of the latter to intercouple said second electric motor and said high and low side conductors to apply an operating potential to said second electric motor and to maintain said second electric motor operated during a second period of time in which rounds of coded current impulses representative of a supervisory type occurrence are applied to said supervisory communication line.

7. An electrical protection system of the type in which the happening of alarm and supervisory-type occurrences at a protected place as indicated by operation of respective contacts of respective alarm and supervisory sensing devices at said protected place are signaled to a remote place by means of respectively different numbers of rounds of coded current impulses on alarm and supervisory communication lines joining said places. comprising:

a. a power supply unit having:

1. a primary source of DC operating potential comprising a rectified commercial power source;

2. a secondary source of DC operating potential comprising a local battery coupled across said primary source to maintain the charge of said local battery and to provide an operating potential in the event of failure of said commercial power;

. high and low side conductors coupled respectively to highand low-potential sides of said primary and secondary sources;

4. a power supervisory circuit comprising a relay and a transistor coupled in series between said high and low side conductors and arranged, upon conduction of said transistor, to energize said delay;

5. a voltage sensitive circuit coupled between said high and low side conductors and having an intermediate potential point coupled to an element of said transistor to provide a bias potential thereto, said voltage sensitive circuit being arranged, when the voltage between said conductors at least equals a selected value to render said transistor conductive and when said voltage between said conductors falls below said selected value to render said transistor nonconductive thereby to deenergize said relay;

all.

6. a high side output terminal;

7. means including a first armature and front contact of said relay to connect said output terminal to said high side conductor; and

8. a tertiary source of DC operating potential comprising an additional battery having its low side connected to said low side conductor and having its high side connected to a back contact of said relay associated with said first armature;

. an alarm transmitter having:

I an alarm signal code wheel;

2. an alarm signaling circuit electrically coupled to said alarm code wheel for delivering rounds of coded current impulses to said alarm communication lines upon operation of said alarm signal code wheel;

3 a first plurality of cam-operated switches having a plurality of successive switching positions;

4. a first electric motor operatively coupled to said alarm signal code wheel and to said first cam-operated switches to operate said alarm signal code wheel and said first cam-operated switches when operating potential is applied to said first motor;

. first operable circuit means including switches of said first plurality and contacts of at least one of said alarm sensing devices and arranged upon operation of the latter to intercouple said first electric motor, said output terminal and said low side conductor to apply an operating potential to said first electric motor and to maintain said first electric motor operated during a first period of time in which selected rounds of coded current impulses representative of an alarm are applied to said alarm communication line;

6. first braking means for said first electric motor;

means included in said first circuit means and comprising a second armature and back contact of said first relay to energize said electric motor for a second period shorter than said first period whereby coded current impulses characteristic of trouble are applied to said alarm communication lines upon deenergization of said first relay; and

. a supervisory transmitter having:

l. a supervisory signal code wheel;

2. a supervisory signaling circuit electrically coupled to said supervisory code wheel for delivering rounds of coded current impulses to said supervisory communication line upon operation of said supervisory signal code wheel;

3. a second plurality of cam-operated switches having a plurality of successive switching positions;

4. a second electric motor operatively coupled to said supervisory signal code wheel and to said second camoperated switches to operate said supervisory code wheel and said second cam-operated switches when operating potential is applied to said second motor;

5. second operable circuit means including switches of said second plurality and contacts of at least one of said supervisory sensing devices and arranged upon operation of the latter to intercouple said second electric motor and said high and low side conductors to apply an operating potential to said second electric motor and to maintain said second electric motor operated during a third period of time in which rounds of coded current impulses representative of a supervisory type occurrence are applied to said supervisory communication line;

6. second braking means for said second electric motor;

and

7. means including a cam-operated switch of said second plurality to operatively couple said second braking means and said second electric motor to stop the latter upon completion of said third period.

8. An electrical protection system as set forth in claim 7 in which said first circuit means of said alarm transmitter ineludes:

i. a normally energized second relay coupled to said contacts of said alarm detecting devices and arranged to be deenergized upon occurrence of a circuit ground affecting said contacts; and

ii. means including contacts of said second relay arranged to operate said electric motor for said second period upon deenergization of said second relay.

9. An electrical protection system as set forth in claim 8 in which said low side conductor is coupled to ground and in which a switch element of said first plurality is included in said coupling, said switch element being open at completion of said second period to prevent continued operation of said first electric motor through said circuit ground.

10. An electrical protection system as set forth in claim 7 in which said first circuit means of said alarm transmitter is arranged upon occurrence of an open affecting said contacts of said alarm detecting devices to operate said electric motor for said second period.

11. An electrical protection system as set forth in claim 7 in which each of said operable circuit means includes externally operable switching means arranged, when operated, to apply operating potentials to said respective electric motors for a time period selected to cause said code wheels to apply restoration rounds of coded impulses to said respective communication lines.

12. In an electrical protection system of the type in which the happening of alarm and supervisory-type occurrences at a protected place as indicated by operation of respective contacts of respective alarm and supervisory sensing devices at said protected place are signaled to a remote place by means of operation of alarm and supervisory transmitters, respectively, which apply rounds of coded current impulses on alarm and supervisory communication lines joining said places, a power supply unit comprising:

l. a primary source of DC operating potential comprising a rectified commercial power source;

2. a secondary source of DC operating potential comprising a local battery coupled across said primary source to maintain the charge of said local battery and to provide an operating potential in the event of failure of said commercial power;

3. high and low side conductors coupled respectively to high and low potential sides of said primary and secondary sources;

4. a power supervisory circuit comprising a relay and a transistor coupled in series between said high and low side conductors and arranged, upon conduction of said transistor, to energize said relay;

5. a voltage-sensitive circuit coupled between said high and low side conductors and having an intermediate potential point coupled to an element of said transistor to provide a bias potential thereto, said voltage-sensitive circuit being arranged, when the voltage between said conductors at least equals a selected value to render said transistor conductive and when said voltage between said conductors falls below said selected value to render said transistor nonconductive thereby to deenergize said relay;

6. a high side output terminal;

7. means including a first armature and front contact of said relay to connect said output terminal to said high side conductor;

8. a tertiary source of DC operating potential comprising an additional battery having its low side connected to said low side conductor and having its high side connected to a back contact of said relay associated with said first armature;

9. means intercoupling said output terminal and said low side conductor to one of said transmitters to provide operating potential thereto when any of said power sources is connected to said terminal; and

I0. means intercoupling said high and low side conductors and the other one of said transmitters to apply operating potential thereto from said primary and secondary power sources a a a a s Patent No. 3 ,6l8,069 Dated November 2, 1971 Inventor) Francis C. Evans and Fred 0. Johns It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 8 "protective" should be protection Col. 1, line 64 "particular" should be must Col. 1, line 68 "receiving" should be warning Col. 5, line 26 after contact insert K3-3 shunts the 8 loop and opening of switch element Col. 8, line 9 "26" should be 25 Col. 8, line 20 "Ll-S" should be Kl-S Col. 9, line 37 should be Col. 9, line 38 "z" should be Col. 9, line 44 "z" should be Col. 11, line 65 "delay" should be relay Col. 12, after line 33 insert the following:

- 7. means including a cam operated switch of said first plurality to operatively couple said first braking means and said first electric motor to stop the latter upon completion of said selected rounds; and

301. 12, line 34 "7" should be 8 Signed and sealed this 13th day of June 1972.

SEAL) httest:

:DWARD M.FLETCHER,JR. ROBERT GOTTSCHALK .ttesting Officer Commissioner of Patents po'mso 0&9, USCOMM-DC 60376-P69 

1. An electrical protection system of the type in which the happening of occurrences at a protected place as indicated by operation of one or more condition-sensing devices at said protected place are signaled to a remote place by means of one or more rounds of coded current impulses on a communication line joining said places, comprising: a. a power supply unit having:
 1. a primary source of DC operating potential;
 2. a secondary source of DC operating potential coupled across said primary source to provide an operating potential in the event of failure of said primary source:
 3. an output terminal:
 4. current and voltage responsive means coupled across said primary and secondary sources and having transfer contacts arranged to connect said primary and secondary sources to said output terminal when either of said primary and secondary sources have a voltage equal to or above a selected level:
 5. a tertiary source of DC operating potential normally electrically isolated from said primary and secondary sources and from said output terminal; and
 6. means including said transfer contacts to interconnect said tertiary source and said output terminal when both of said primary and secondary sources have a voltage below said selected level; b. a transmitter having:
 1. a code wheel;
 2. an output signaling circuit electrically coupled to said code wheel for delivering rounds of current impulses to said communication line upon operation of said code wheel;
 3. a multielement switching mechanism having a plurality of successive switching positions;
 4. an electric motor operatively coupled to said code wheel and said switching mechanism to operate said code wheel and said switching mechanism when operating potential is applied to said motor;
 5. operable circuit means including elements of said switching mechanism and interconnecting said electric motor and said output terminal and arranged, when operated, to apply operating potential to said electric motor;
 6. electrical control means operatively associated with one or more of said condition sensing devices and electrically associated with said circuit means for operating the latter upon operation of one or more of said condition sensing devices whereby said circuit means applies operating potential to said electric motor and said wheel supplies current impulses to said output signaling circuit; and
 7. braking means responsive to current impulses coupled with said electric motor and arranged to stop the latter after a predetermined number of rounds of current impulses have been delivered to said output signaling circuit.
 2. a secondary source of DC operating potential coupled across said primary source to provide an operating potential in the event of failure of said primary source:
 2. an output signaling circuit electrically coupled to said code wheel for delivering rounds of current impulses to said communication line upon operation of said code wheel;
 2. An electrical protection system as set forth in claim 1 in which said transmitter is provided with an additional electrical control means operatively associated with said current and voltage responsive means and electrically associated with said circuit means for operating the latter when both of said primary and secondary sources have a voltage below said selected level.
 2. a secondary source of DC operating potential coupled across said primary source to provide an operating potential in the event of failure of said primary source;
 2. an alarm signaling circuit electrically coupled to said alarm code wheel for delivering rounds of coded current impulses to said alarm communication lines upon operation of said alarm signal code wheel;
 2. a supervisory signaling circuit electrically coupled to said supervisory code wheel for delivering rounds of coded current impulses to said supervisory communication line upon operation of said supervisory signal code wheel;
 2. a secondary source of DC operating potential comprising a local battery coupled across said primary source to maintain the charge of said local battery and to provide an operating potential in the event of failure of said commercial power;
 2. an alarm signaling circuit electrically coupled to said alarm code wheel for delivering rounds of coded current impulses to said alarm communication lines upon operation of said alarm signal code wheel; 3 a first plurality of cam-operated switches having a plurality of successive switching positions;
 2. a supervisory signaling circuit electrically coupled to said supervisory code wheel for delivering rounds of coded current impulses to said supervisory communication line upon operation of said supervisory signal code wheel;
 2. a secondary source of DC operating potential comprising a local battery coupled across said primary soUrce to maintain the charge of said local battery and to provide an operating potential in the event of failure of said commercial power;
 3. high and low side conductors coupled respectively to high and low potential sides of said primary and secondary sources;
 3. a second plurality of cam-operated switches having a plurality of successive switching positions;
 3. high and low side conductors coupled respectively to high-and low-potential sides of said primary and secondary sources;
 3. a second plurality of cam operated switches having a plurality of successive switching positions;
 3. a first plurality of cam operated switches having a plurality of successive switching positions;
 3. high and low side conductors coupled respectively to high and low potential sides of said primary and secondary sources;
 3. An electrical protection system as set forth in claim 2 in which said circuit means is provided with switching elements effective when said circuit means is operated by said additional electrical control means to cause a distinctive number of rounds of current impulses to be supplied to said output signaling circuit.
 3. a multielement switching mechanism having a plurality of successive switching positions;
 3. an output terminal:
 4. current and voltage responsive means coupled across said primary and secondary sources and having transfer contacts arranged to connect said primary and secondary sources to said output terminal when either of said primary and secondary sources have a voltage equal to or above a selected level:
 4. an electric motor operatively coupled to said code wheel and said switching mechanism to operate said code wheel and said switching mechanism when operating potential is applied to said motor;
 4. An electrical protection system as set forth in claim 1 in which there are provided a plurality of said transmitters.
 4. a power supervisory circuit comprising a relay and a transistor coupled between said high and low side conductors and arranged, upon a change in conductive condition of said transistor, to operate said relay;
 4. a first electric motor operatively coupled to said alarm signal code wheel and to said first cam-operated switches to operate said alarm signal code wheel and said first cam-operated switches when operating potential is applied to said first motor;
 4. a second electric motor operatively coupled to said supervisory signal code wheel and to said second cam-operated switches to operate said supervisory code wheel and said second cam-operated switches when operating potential is applied to said second motor; and
 4. a power supervisory circuit comprising a relay and a transistor coupled in series between said high and low side conductors and arranged, upon conduction of said transistor, to energize said delay;
 4. a first electric motor operatively coupled to said alarm signal code wheel and to said first cam-operated switches to operate said alarm signal code wheel and said first cam-operated switches when operating potential is applied to said first motor;
 4. a second electric motor operatively coupled to said supervisory signal code wheel and to said second cam-operated switches to operate said supervisory code wheel and said second cam-operated switches when operating potential is applied to said second motor;
 4. a power supervisory circuit comprising a relay and a transistor coupled in series between said high and low side conductors and arranged, upon conduction of said transistor, to energize said relay;
 5. a voltage-sensitive circuit coupled between said high and low side conductors and having an intermediate potential point coupled to an element of said transistor to provide a bias potential thereto, said voltage-sensitive circuit being arranged, when the voltage between said conductors at least equals a selected value to render said transistor conductive and when said voltage between said conductors falls below said selected value to render said transistor nonconductive thereby to deenergize said relay;
 5. second operable circuit means including switches of said second plurality and contacts of at least one of said supervisory sensing devices and arranged upon operation of the latter to intercouple said second electric motor and said high and low side conductors to apply an operating potential to said second electric motor and to maintain said second electric motor operated during a third period of time in which rounds of coded current impulses representative of a supervisory type occurrence are applied to said supervisory communication line;
 5. first operable circuit means including switches of said first plurality and contacts of at least one of said alarm sensing devices and arranged upon operation of the latter to intercouple said first electric motor, said output terminal and said low side conductor to apply an operating potential to said first electric motor and to maintain said first electric motor operated during a first period of time in which selected rounds of coded current impulses representative of an alarm are applied to said alarm communication line;
 5. a voltage sensitive circuit coupled between said high and low side conductors and having an intermediate potential point coupled to an element of said transistor to provide a bias potential thereto, said voltage sensitive circuit being arranged, when the voltage between said conductors at least equals a selected value to render said transistor conductive and when said voltage between said conductors falls below said selected value to render said transistor nonconductive thereby to deenergize said relay;
 5. second operable circuit means including Switches of said second plurality and contacts of at least one of said supervisory sensing devices and arranged upon operation of the latter to intercouple said second electric motor and said high and low side conductors to apply an operating potential to said second electric motor and to maintain said second electric motor operated during a second period of time in which rounds of coded current impulses representative of a supervisory type occurrence are applied to said supervisory communication line.
 5. first operable circuit means including switches of said first plurality and contacts of at least one of said alarm sensing devices and arranged upon operation of the latter to intercouple said first electric motor, said output terminal and said low side conductor to apply an operating potential to said first electric motor and to maintain said first electric motor operated during a first period of time in which selected rounds of coded current impulses representative of an alarm are applied to said alarm communication line; and c. a supervisory transmitter having:
 5. a voltage sensitive circuit coupled between said high and low side conductors and having an intermediate potential point coupled to an element of said transistor to provide a bias potential thereto, said voltage sensitive circuit being arranged, when the voltage between said conductors at least equals a selected value to place said transistor in a selected conductive condition and when said voltage between said conductors falls below said selected value to place said transistor in a different conductive condition thereby to operate said relay;
 5. An electrical protection system as set forth in claim 4 in which at least a selected one but not all of said transmitters have the operable circuit means thereof connected to said primary and secondary sources and in which said power supply is provided with means electrically to isolate said selected one or more of said transmitters from said tertiary source when said tertiary source is connected to said output terminaL of said power supply.
 5. operable circuit means including elements of said switching mechanism and interconnecting said electric motor and said output terminal and arranged, when operated, to apply operating potential to said electric motor;
 5. a tertiary source of DC operating potential normally electrically isolated from said primary and secondary sources and from said output terminal; and
 6. means including said transfer contacts to interconnect said tertiary source and said output terminal when both of said primary and secondary sources have a voltage below said selected level; b. a transmitter having:
 6. electrical control means operatively associated with one or more of said condition sensing devices and electrically associated with said circuit means for operating the latter upon operation of one or more of said condition sensing devices whereby said circuit means applies operating potential to said electric motor and said wheel supplies current impulses to said output signaling circuit; and
 6. An electrical protection system of the type in which the happening of alarm and supervisory-type occurrences at a protected place as indicated by operation of respective contacts of respective alarm and supervisory sensing devices at said protected place are signaled to a remote place by means of rounds of coded current impulses on alarm and supervisory communication lines joining said places, comprising: a. a power supply unit having:
 6. a high side output terminal;
 6. a high side output terminal;
 6. first braking means for said first electric motor;
 6. second braking means for said second electric motor; and
 6. a high side output terminal;
 7. means including a first armature and front contact of said relay to connect said output terminal to said high side conductor;
 7. means including a cam-operated switch of said second plurality to operatively couple said second braking means and said second electric motor to stop the latter upon completion of said third period.
 7. means included in said first circuit means and comprising a second armature and back contAct of said first relay to energize said electric motor for a second period shorter than said first period whereby coded current impulses characteristic of trouble are applied to said alarm communication lines upon deenergization of said first relay; and c. a supervisory transmitter having:
 7. means including a first armature and front contact of said relay to connect said output terminal to said high side conductor; and
 7. An electrical protection system of the type in which the happening of alarm and supervisory-type occurrences at a protected place as indicated by operation of respective contacts of respective alarm and supervisory sensing devices at said protected place are signaled to a remote place by means of respectively different numbers of rounds of coded current impulses on alarm and supervisory communication lines joining said places, comprising: a. a power supply unit having:
 7. means including an armature and contact of said relay to connect said output terminal to said high side conductor; and
 7. braking means responsive to current impulses coupled with said electric motor and arranged to stop the latter after a predetermined number of rounds of current impulses have been delivered to said output signaling circuit.
 8. a tertiary source of DC operating potential comprising a local battery having its low side connected to said low side conductor and having its high side connected to another contact of said relay associated with said armature; b. an alarm transmitter having:
 8. a tertiary source of DC operating potential comprising an additional battery having its low side connected to said low side conductor and having its high side connected to a back contact of said relay associated with said first armature; b. an alarm transmitter having:
 8. An electrical protection system as set forth in claim 7 in which said first circuit means of said alarm transmitter includes: i. a normally energized second relay coupled to said contacts of said alarm detecting devices and arranged to be deenergized upon occurrence of a circuit ground affecting said contacts; and ii. means including contacts of said second relay arranged to operate said electric motor for said second period upon deenergization of said second relay.
 8. a tertiary source of DC operating potential comprising an additional battery having its low side connected to said low side conductor and having its high side connected to a back contact of said relay associated with said first armature;
 9. means intercoupling said output terminal and said low side conductor to one of said transmitters to provide operating potential thereto when any of said power sources is connected to said terminal; and
 9. An electrical protection system as set forth in claim 8 in which said low side conductor is coupled to ground and in which a switch element of said first plurality is included in said coupling, said switch element being open at completion of said second period to prevent continued operation of said first electric motor through said circuit ground.
 10. An electrical protection system as set forth in claim 7 in which said first circuit means of said alarm transmitter is arranged upon occurrence of an open affecting said contacts of said alarm detecting devices to operate said electric motor for said second period.
 10. means intercoupling said high and low side conductors and the other one of said transmitters to apply operating potential thereto from said primary and secondary power sources.
 11. An electrical protection system as set forth in claim 7 in which each of said operable circuit means includes externally operable switching means arranged, when operated, to apply operating potentials to said respective electric motors for a time period selected to cause said code wheels to apply restoration rounds of coded impulses to said respective communication lines.
 12. In an electrical protection system of the type in which the happening of alarm and supervisory-type occurrences at a protected place as indicated by operation of respective contacts of respective alarm and supervisory sensing devices at said protected place are signaled to a remote place by means of operation of alarm and supervisory transmitters, respectively, which apply rounds of coded current impulses on alarm and supervisory communication lines joining said places, a power supply unit comprising: 